Optical fiber transceivers launch and receive light from optical fiber cables. Optical fiber cables are subject to mechanical loading during installation and use. During use, the cables are transmitting optical signals, and mechanical loading on the cables, such as tugging or pulling forces exerted on the cables, can degrade the optical signal by reducing the optical coupling efficiency between the optical fiber and the transmitter port of the transceiver. The problem is referred to in the optical communications industry as “wiggle” or “wiggle losses”.
A variety of techniques have been used to eliminate or reduce wiggle and wiggle loss. One technique involves permanently fusing an optical fiber of an optical fiber cable to the transmitter port of the transceiver. This configuration is commonly referred to as a pigtail. One disadvantage of this approach is that the fiber cannot be unplugged from the transmitter module. In many cases, it is desirable to be able to unplug an optical fiber cable from one transmitter port and plug it into a different transmitter port. Fusing a fiber to a transmitter port obviously eliminates this possibility.
Another technique involves using a split-sleeve receptacle having a rigidly mounted port. With this technique, an optical fiber cable plugs into a receptacle of the transceiver. The optical fiber within the optical fiber cable is surrounded by a precisely ground ceramic ferrule, which is guided into the receptacle by a precisely formed sleeve of the receptacle. This sleeve has a split that is compressed into a final inner diameter once the cable has been inserted into the receptacle so that the inner diameter of the sleeve closely matches the outer diameter of the ferrule. Unfortunately, the split also weakens the sleeve, allowing the ferrule to move with respect to the transmitter when the fiber cable is loaded, which results in wiggle loss.
Another technique involves using a solid-sleeve receptacle having a rigidly mounted port. With this technique, the optical fiber cable plugs into a transceiver receptacle. The optical fiber in the optical fiber cable is surrounded by a precisely ground ceramic ferrule, which is guided into the receptacle by a precisely formed sleeve. This sleeve does not have a split, but is a complete cylinder (i.e., like a gun barrel) having an inner diameter that is intended to precisely match the diameter of the ferrule. The disadvantage of this configuration is that the inner diameter of the sleeve and the diameter of the ferrule often do not precisely match each other due to variations in ferrule diameter. Because the sleeve is solid and cannot be precisely compressed to achieve the exact inner diameter needed to precisely match the ferrule diameter, a relatively poor alignment of the optical fiber to the transmitter obtained. This results in optical losses that vary in accordance with variations in the ferrule diameter.
A need exists for a transmitter port of a transceiver that provides improved optical coupling efficiency between a transmitter port of a transceiver and an optical fiber of an optical fiber cable.